In particular, yet not restrictive manner, the invention concerns a tongue for a floor panel and a set of floor panels mechanically joined to preferably a floating floor. However, the invention is as well applicable to building panels in general. More particularly invention relates to the type of mechanically locking systems comprising a flexible or partly flexible tongue and/or displaceable tongue, in order to facilitate the installation of building panels
A floor panel of this type is presented in WO2006/043893, which discloses a floor panel with a locking system comprising a locking element cooperating with a locking groove, for horizontal locking, and a flexible tongue cooperating with a tongue groove, for locking in a vertical direction. The flexible tongue bends in the horizontal plane during connection of the floor panels and makes it possible to install the panels by vertical folding or solely by vertical movement. By “vertical folding” is meant a connection of three panels where a first and second panel are in a connected state and where a single angling action connects two perpendicular edges of a new panel, at the same time, to the first and second panel. Such a connection takes place for example when a long side of the first panel in a first row is already connected to a long side of a second panel in a second row. The third panel is then connected by angling to the long side of the first panel in the first row. This specific type of angling action, which also connects the short side of the new panel and second panel, is referred to as “vertical folding”. It is also possible to connect two panels by lowering a whole panel solely by vertical movement against another panel.
Similar floor panels are further described in WO2003/016654, which discloses locking system comprising a tongue with a flexible tab. The tongue is extending and bending essentially in a vertical direction and the tip of the tab cooperates with a tongue groove for vertical locking.